Two pro football players who have been outspoken advocates of gay rights have added their voices to those calling for the U.S. Supreme Court to strike down California's ban on same-sex marriage.

"For far too long, professional sports have been a bastion of bigotry, intolerance and small-minded prejudice toward sexual orientation, just as they had been to racial differences decades earlier," lawyers for Brendon Ayanbadejo and Chris Kluwe said Thursday in a filing to the court.

That attitude is starting to change, they said, as sports leagues, teams and players "are finally speaking out against homophobia" and "tolerance is becoming the message in locker rooms."

Still, not one male professional athlete in a major sport has come out as gay, and the court's ruling will reverberate through the sports world as it will through the entire nation, the lawyers said.

It was one of nearly 50 briefs submitted by opponents of Proposition 8, the 2008 California initiative that defined marriage as the union of a man and a woman. The court will hear arguments March 26 on the measure, which lower courts have declared unconstitutional.

Ayanbadejo, a linebacker for the Super Bowl champion Baltimore Ravens, and Kluwe, a punter with the Minnesota Vikings, have been the most visible National Football League players to speak up on behalf of gays, particularly their right to marry.

When a Maryland state representative wrote to the Ravens owner in August telling him to "inhibit such expressions" from Ayanbadejo, the player refused to keep silent, noting that his own parents' interracial marriage would once have been illegal. The team backed him, and Kluwe came to Ayanbadejo's support with an online letter asking the legislator, "Why do you hate freedom?"

Ayanbadejo, 36, went to high school in Santa Cruz. Both he and Kluwe, 31, attended UCLA.

In their brief, they argued that prohibiting gays and lesbians from marrying their chosen partners violates not only the constitutional guarantee of equality but also concepts of fairness that are essential in athletics.

"Just as athletes should be judged, not by their sexual orientation, but by their performance and the way they treat their teammates," they said, "so too should people be judged as citizens by how they act and treat others, and not what they inherently are."